The objective of this proposed project is to transform the data collection technology used to assess function and disability in older adults. The proposal responds to NIA's stated priority listed in PA-04-064 to "develop new products that improve data collection, data analysis, and data dissemination of gerontological research." Traditional, fixed-form outcome instruments present serious measurement and practical requirements to identify, track, and evaluate change in function and disability across older age-groups. To address these deficiencies, the principal aims of Phase I are to: (1) build a prototype computerized adaptive testing (CAT) instrument based on an existing Late-Life Function & Disability Instrument (LL-FDI); (2) compare the accuracy, response burden, and sensitivity to change of the prototype LLFDI-CAT with the full-length LL-FDI instrument (LLFDI-Fixed) from an existing database; and (3) evaluate scoring comparability, respondent burden and acceptance of parallel versions of the LLFDI-Fixed and LLFDI-CAT in a pilot test with a sample [unreadable] of disabled older adults. The product in Phase I will be a prototype version of a LLFDI-CAT. In Phase II of the research project, we will examine item calibrations of the original LL-FDI, add new items to broaden the range of coverage and fill in identified gaps, conduct a field study to re-calibrate items, create algorithms for a fully operational LLFDI-CAT system, and implement a dissemination plan. The LLFDI-CAT will fill a critical void for a feasible and psychometrically superior assessment instrument to be used in gerontological research where outcome measures are needed that are comprehensive, sensitive to change, and practical. Relevance to Public Health: Improved instruments are critical for use in and for use in public health research where outcome measures are needed that are comprehensive and sensitive to meaningful change related to interventions designed to improve the health and functioning of older adults and to test the effectiveness of new clinical treatments and interventions. The product of this STTR project will be a marketable Computer Adapted Testing (CAT) version of the Late Life-FDI, an instrument that has great promise to improve function and disability assessment in older persons. Adapted from the Late-Life FDI, this contemporary assessment technology will fill a critical void for a practical and psychometrically superior system that is not currently available for use in [unreadable] public health research. The public health research and clinical communities would be the likely markets [unreadable] interested in the CAT technology that would be developed and evaluated in this STTR. [unreadable] [unreadable] [unreadable] [unreadable]